The present invention generally concerns a photographic camera and particularly, a miniature camera having a retractable focusable objective lens.
In copending patent application Ser. No. 100,358 entitled "Camera Having an Independently Focused Retractable Objective Lens," filed Dec. 5, 1979, now U.S. Pat. No. 4,280,762, a camera is disclosed which has a relatively small size when the objective lens is retracted. It has good handling, a control means for focusing the camera and viewing through the viewfinder which all facilitate the quick, simple taking of snap-shots.
In the above-described camera, the objective tube is spring-biased in its extended position against an adjustable cam which accomplishes the focusing of the camera. Additionally, the same spring force is primarily responsible for extending the objective tube from its retracted position to its extended position. Thus, it is desirable on one hand to have a relatively strong spring force to extend the objective tube and at the same time maintain the objective tube in firm contact with the cam for focusing purposes and on the other hand for ease of focusing and to reduce frictional loads, it is desirable to have a very light biasing of the tube. An additional problem occurs when a relatively light spring is used in that a very small accidental pressure on the side of the objective tube can cause the tube to deflect so that the camera is not focused.
The conflicting interests created by wanting a strong spring on one hand and a weak spring on the other requires a compromise which does not optimally satisfy either of the two requirements.